Method of obtaining argon and rare atmospheric gases.



J.B.BUCHER METHOD 0F OBTAINING AEGON AND RARE ATMOSPHERIC GASES.

ArfLloATIo'N HLBD 114130.15, 191s. Lw L Patented Aug. 11, 1914:..

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JoHN E. DUCHEE, oE- covENTEY, RHODE isLAND, nssren on To nrrnoniprnonoors COMPANY, or PEoviDENcE, RHODE ISLAND, A conronarron or' RHODE ISLAND.

METHOD or oETAININscAEGon AND RARE ATMosrHEEIo GAsEs.

Original application filed July 24, 1912, Serial Specicatois Letters Patent.

Patented Aug. 11, 1914i.

No. 71i\211. Divided and this application ined December 15, 19,13. Serial Nn,` k80l'5,71-7.

To all who'pitmay concern Be it/lnown that I, `JOHN E. BUGHER, a citizen of the United States, residino at Coventry, in the county of Kent and State of Rhode Island, have invented certain new and useful improvements in Methods of Obtaining Argon and Rare Atmospheric Gases, of which the following is a specification. l y

This invention relates to the production of argon and incidentally the other r`are inert atmospheric gases helium, krypton, neon and xeon, and more particularly to a process of obtaining said gases from atmospheric nitrogen. u

The present application is a division of my application for United States Letters Patent relating' to the synthetic production of cyanogen compounds and the like, filed in the United States Patent vOffice July 24, 1912, and being there designated Serial No. 711,211.

As is well known nitrogen yhas heretofore been regarded as a relatively inert gas while argon has, up tothe present time, been found to be absolutely incapable of being united with any other element.

The present process, in its preferred form, involves the direct union of the elements foi-ming, for example, alkali cyanids,to wit, an alkali metal, carbon and' nitrogen, as a means for effecting the separation of atmospheric nitrogen from the argon.

l have endeavored in various Ways-to directly combine carbon free nitrogen and sodium, for example, andl find that unless u eatalyzer be present the direct synthesis v,cannot be o'lfoctod to any practicable extent. have further found that iron is onel of the most efiicient catalytic agents thatv can vbe used in this connection. l have also become y aware, as a result of an extensive series of l experiments, that sodium carbonate may be oliicicntly converted into sodium cyanid and lia-ve made application for Letters` Patent hercon, said application' being designated Ser. No. 726,924, tiled October 21, 1912 and entitled process for fiiiing atmospheric nitrogen.

The preferred mde of conducting'my process for the production of argon, herein described merely by Way of cxeinplication,

1s more particularly concerned with that phase of the problem which involves the use of metallic sodium, or the like. The lat ter permits the employment of relatively low temperatures,ivhereas With sodium carbonate, for example, agrelatively high temperature is yrequired to combi-neythe sodium of said carthereof, for the economic production of alkali metal cyanids by synthesis. that oxygen. from whatever source, siould' be excluded. from the zone in which the cyanid forming' reaction occurs.

The accompanying drawing); exempliies one of many forms of apparatus in or by means of which my novelv processnur,v be effectuated. lam aware,'ho\vevor, thaivarions modifications and 'changes' may be made' in both the 'process and apparatus, Within the purview of my invention, and hence desire to be limited only by the scope of the claims appended hert-o.

The apparatus. herein described is substantially the same as that described in my application relating to a process' for purifying metals, said application having been lcd iii-thc United States Patent Office Feb- .ruary 8, 1912, and being there designated 'Serial Number 676,399.

Referring to the accompanying draivinfr,

which forms a art hereof ,and in which like reference characters designate like parts in the respective views, Figure 1 is a side elevation of an apparatus wherein my procv ess may be carried out, one side of the munie vsurrounding the,4 retort being removed for purposes of illustration. Fig. 2 is asection of said apparatus taken on line 2-2 of Fig. 1.

A section of heavy weight iron pipe l is provided at either extremity thereof with a reducing ca 2, the reduced extremities of these pipes eing respectively connected to pipes 3 and 4, the latter being preferably of considerably smaller diameter than the sec ioo tion 1. A T 5 is connected to the outer extremity of the small pipe or nipple 3, and a nipple 6 of the same diameter may be tapped into the opposite side of the T 5. Nipple 6 "is connected Ito a cock 7, which in turn is connected to a coupling 8. The nipple or pipe section 4: is also correspondingly connected to a coupling9. Two Ts -10, one of which is disposed upon either side of the retort formed by the tube 1, are connected respectively with couplings 8 and 9 in any suitable manner, while a U-shaped pipe connection 11, having' therein a coupling` 12 and cock 13, afford a by-pass around the retort. Downwardly extending from the T5 is a pipe connection 111 having therein a` cock 15 and laterally extending from the T 10 is a connection 16 in which is a cock 17. The retort 1 may be heated in any suitable manner, as by means of a 'series of Bunsen burners 1S which for :convenience may be mounted upon a common base 19 in a well knownv manner. A screen 2O of lire brick, 4or ythe like, preferably having substantiallyA the form of an inverted U, may surround the.

retort and its burners. Suitable 4vents 421,

for the escape of gases 0f combustion, and

apertures Q2 for the admission of air, Should preferably be provided at intervals along the length of the Inutile. Assuming that iron is the catalytic material used, a suitable quantity thereof may be disposed substantially in the middle of the retort, as in dicated at I find in practice that if the iron be finely divided, e. g., pulverulent or tihmus, the reactions are effected more rapidly than if the said metal be in larger masses. The. reaction, however, may be made so vigorous as to de-carburize solid masses of steel, in which case, of course, the catalytic agent is the iron present in the steel. l have also successfully treated pigiron herein. rEhe catalytic metal, preferably thoroughly and intimately mixed with pulyverulcnt carbon, c. g., graphite, so that the extended surface of the catal tic metal mav be woll in contact with the carbon, as hereinafter described, may be introduced into the retort by unscreiving one of the reducers 2, and similarly introduce at one end of the retort a quantity of alkali vme'ital, e. g.,

sodium. Nitrogen is introduced int-o the be closed, the gaseous nitrogen will passthe catalytic metal or material 23. The carbon may also be supplied by injecting hydrocarbons, e. g. petroleum through pipe 24 together with the nitrogen; the'useof such carbonaceous materials being hereinafter more filly discussed.'

In the device shown, 2O burners have 'been in practice a few of these at the extremity of the retort fromwhichthe current of -nitrogen emerges, are unlighted. Thus, for example, gas jets may be ignited, and 5 burners may be left unlighted. As a result the said extremity of the retort from which the nitrogen emerges is cooler than other portions ofthe same and is preferably at a alkali metal, e. g., sodium, so that any sodium which lpasses through the mass of catalytic material will, upon entering this relatively cool end of the retort, be deposited.

alk'alimetal which accumulates in this rela- ,tivelycool extremity of the retort and is .there held until the current of nitrogen is reversed, in the manner hereinafter defscribed. The nitrogen or argon which passes 'out of the apparatus should preferably be quite cool, and as-it passes olf through the :cock 17, it may be collected in any suitable all of the sodium, if sodium be the alkali metalemployed, has been transferred from .one end of the retort to the other, .the cocks 7 and 17 are closed and those designated 13 and 15 are opened. Thereafter the nitrogen will pass downwardly from T 10 and around a by-pass 11 to T 10', and thence through the retort l in a reverse direct-ion to that in which it previously owed therethrough'. It will be understood that before so reversing previously v,been unlighted are-now lighted, 4and a corresponding number at t-he other extremity of |`the retort are turned olf. As a result, the dol section or'portionv of the relatter to the other, so that the previously deposited sodium, for example, will be reevaporated and will again be carried through --or over the catalytic material, by the nitrogen current, to be deposited thereafter at the came. The flow of nitrogen through the retort may thus be reversed at intervalsv until substantially alloof the alkali metal has been used up. It is obviousthat this metal may be introduced into the retort or vessel either in liquid or in solid form, or it may indicate that the higher the temperature of the operation the more rapid the etfectuation of the process. There are, however, limits beyond which it would `be undesirable to go.

In operating \tl1e apparatus herein partemperature below the boiling point of the `tort is reversed from one' extremity of thev y end of the retort from whence it originally b e introduced as a vapor. My experiments somewhat diagrammatically' indicated and A This --procedure results in aisaving of the Ilianner to avoid waste. After substantially v the current of gas, the burners 18, which had ticularly described, the temperature was maintained by means of the burners at from ,7000 to 800o C. I have found, however, that where the iron was in finely divided condition, and Where the carbon was present in proper proportion to the iron, and especially Where the said carbon was in the form of graphite, the reactions took place so vigleast.

orously thatl some of the iron was melted into globules, which would indicate that the temperature of some of the iron had been raised to the neighborhood of 1200O C., at

Under these last mentioned conditions, the demand for nitrogen is so great that a rapid stream of the same must be passed into the retort, as the reactions tend to form a partial vacuum therein and it is necessary in" such case to uard against a flow of gas back through t e cock 17. To this end a liquid seal 26, or the like, may be provided. Vith correct proportions of atmospheric nitrogen, carbon and sodium, in

the foregoing case, and With the/iron actively present greatly in excess .of the active carbon present, the small quantity of gas escaping through ,the tube 29 was practically pure argon, substantially all of the nitrogen having been greedily absorbed. Argon may practically only be obtained, of course, from atmospheric nitrogen, and it is assumed that this latter has been obtained by separating it from the oxygen of the air by any suitable process, of Which several commercially practicable ones are known to me, and `'which Will be hereinafter referred to. lVhere an excess of nitrogen passes through the appara tus, it may be collected and may thus be used repeatedly until it has all been conlsumed. Should it be found in` practice that any Wasteof sodium, for example, is tak-ing place, it is merely necessary to refrigerate (as my means, for example, of currents of airy the extremity of t-he retort from Whichthe nitrogen iiows, to such an extent that the temperature of the same will be materially below the boiling point of the alkali metal. It may be here observed, too), that it is advantageous, in such case, to carry out the process under a pressure considerably above atmospheric. This feature is of especial advantage when the nitrogen current must be forced through the mass of catalytic material.

After many experiments and much re search, I have found that carbon suitable for use in this synthetic process of producing alkali cyanids mav also be obtained by heating impure carbon in the electric furnace. It is not necessary to carry the temperature in the electric furnace so high as to produce graphite. In fact, the temperature required is only that sufficientl to drive olf oxygen and oxygen compounds including Graphite is, however, as I have previously intnnated, especially available for use in the process. Many forms of lampblack also, after being heated to a White heat contain very little oxygen and are Well adapted for the purpose. Carbon deposited by or obtained from the decomposition of hydrocarbons at a red heat is also'admirably suited for my process. Hydrocarbon `vapors, such as those obtainedfrom petroleum oils, benzene, (06H8) or other hydrocarbons substantially free from oxygen, may be introduced into the retort.

It ,is essential that an intimate mixture of or contact between the alkali metal, nitrogen, carbon,'and the catalytic agent, be effected.` Iron which is the preferred catalytic agent, is` preferably in the form ot' re duced iron, powdered iron, iron filings, iron turnings, or any form of iron or steel exposing a large surface; and to such iron I broadly apply the term linely divided. It may be here noted that it is of great impoi-tance that a relatively large quantityoltI theI catalytic metal be provided in propor- -tion to the quantity of carbon actively present. The carbon may be deposited upon the extended surface of the catalytic metal in a practically pure state and in `an excellent physical condition for use inthe process. Moreover, under lsuitable conditions, the

.carbon may be deposited in a coherent form and will cling tothe surface of the iron or steel thus allowing the cyanid formed thereupon to separate from the mass lin a clean condition practically free from suspended carbon` The carbon, however, may or may not be deposited previous t'o the introduc tion of the alkali metal and nitrogen, as desired. The hydrocarbon' vapor mayl be passed over the finely divided iron orsteel simultaneously With the vapor of the alkali' metal and nitro-gen; or, the hydrocarbon, for instance', petroleum oil, may be sprayed orinjected into the apparatus with the current of nitrogen. It is not necessary to have the catalytic material e. g., iron or steel, 'present in nely divided condition upon which to deposit the carbon, or in contact therewith; although the formationofalkali cyanid is much more rapid when the catalytic material is in such condition as to present an extended catalytic surface to the cyanid forming element.

If the apparatus is made of steel, or if steel turnings or other finely divided forms of steel are present, the carbon of the steel is taken away by the alkali metal and nitrogen, in the form of alkali cyanid and the steel is changed Ato substantially pure iron. The carbon combined with the iron in steel, seems to be especially Well suited to enter into combination With alkali metal andv nitrogen at the proper temperature; but irany event, the presence of large amounts 1.- finely divided iron or steel relative t ,jte quantity of reacting substances present a portion of the mixture of carbon, alkali metal and nitrogen into the presence of a relatively large amount of iinely divided i iron heated to` an incipient, or very loa7 red heat, toeect an almost 1mmed1ate reaction.

The catalytic agent, e. g., iron may be pulverized or fibrous and the reaction or reactions are eected with much greater rapidity under such conditions than when the catalyzer is present in solid thick masses. Ot' course when the carbon is combined 4With the catalytic element or material, as in iron carbid, the reaction effected removes the carbon from the carbid and leaves the iron to thereafter act as a true catalyzer.

The synthesis -or formation of alkali cyanid being an exo'thermic reaction, suHicient heat is developed thereby to continue the reactionso long as the necessary elements (alkali metal, carbon and nitrogen) are supplied. The initial temperature necessary may be attained by externally heating the reaction vessel, or Aby heating a portion of the mixture in any desired manner to the proper temperature. On an industria-l scale, it' externalheating be the method used, it is desirable to have the Walls of the reaction vessel as thin as practicable in order to attain the necessary 4internal temperature as quickly and 'as economically as possible. Care must be taken to remove all the oxygen gas from the nitrogenY used', because any oxygen entering with the nitrogen will combine With the alkali-metal, thus reducing b y just so much the yield of eyanid at the relatively 4lovv and' economical temperature lemployed. The alkali metal may be sodium, potassium or lithium, or any mixture of these. Lithium, of course, produces lithium cyanid, or the 1ike,/but I prefer to use commercially pure sodium, 'or an alloy of sodium With a heavy metal such as lead. Lithium reacts with the elements carbon, nitrogen and iron as follows 2Li+ac+Ng+ir0n=eineN-Piron.

I have not as yet been able to ascertain Whether the catalytic agent e. g., iron, is as necessary in -the case of lithium as with sodium or potassium; but consider that the catalyzer is of value despite the fact that lithium forms a nitrid, LisN, which might then react With carbon'to form cyanid, even in the absence of iron. I find that on heating calcium to a high temperature with nitrogen, carbon ,and iron, some cyanid is produced, but the quantity is in no way to be compared to that produced by the aid of the alkali metals under similar conditions. If the elements entering -into the synthesis of alkali cyanids are brought together under vof certain chemical industries; etc.

l pressure lhigher than ordinary atmospheric pressure, the fcrmation of cyamd 1s hastened and the capacity of the apparatus is increased. It an alloy of the alkali metal, as for instance, lead-sodium alloy,I to be used, the sodium may be separated from the alloy in any suitable manner as, for example, in the form of vapor, the latter being preferably obtainedv by blowing nitrogen through the alloy at a suitable temperature.'

The nitrogen used in the process may be obtained by any suitable process; as,-from ordinary combustion gases; from liquid a1r by abstracting the oxygen from atmospheric v air by means of metals; as a Waste product If the nitrogen is prepared from atmospheric air it will contain approximately one per cent. of argon, mixed with small quantities of other inert gases such as helium, krypton, neon and xenon, Which' are unchanged by the process of alkali lmetal c'yanid synthesis; and said gases may be allowed to escape from the apparatus at a suitable point and may be collected in a suitable manner, for use in a substantially pure form.

In my co-pending application, Serial No.

076,399, filed February 8, 1912, I have c .onsidered more particularly thedecarburiza-v tionof steel by means of the'reactions which result in the formation of cyanid or the like,

both at temperatures .below Athe melting point of iron, for example, and at temperatures above the same. .I hence do not desire 100 to'be limited to a cherry red heat for the upper limit of temperature in my process, except by an express limitation in the claims, while I lind that in manylcases the process can be effected at a dull red heat or even somewhat lower.` The temperature of the operation may in 'some cases range as loW as 500o C., but as this temperature is ap'- Aproaehed the reaction is less vigorous and so becomes commercially impractical. On the other hand While the reaction may be effected at relatively high temperatures such for example as clear orange'heat, I prefer to operate at a temperature of less than, let us say, 1100o C., owing to the `diiiculty and cost of operating commercially for extended periods at higher temperatures, the cost of operation including, of course, the 1mtial cost of the apparatus used, theupkeep of the same, and the cost lof fuel or' electrical energy used. for developing the operating temperature. Owing. to the exothermio character of the reaction the reacting materials may effect an elevation of their own temperature in portions or the mass, 'but as iar as practicable the bulk oi the substances participating in the forn'iation oi?l the prcductsought are prety `is first formed, ivhieh carbid, or solution,

together with the iron carbid already preslent, it' any, then reacts With nitrogen and sodium, or like metal or element present which is capableof forming the base eta fcyanogen compound AWhich is stable at the ,temperature of the operation, thgronb@ "lution of carbon in iron may, of `cou1se,be

g eliminated from the compound or compounds formed, and the metallic iron thus pfroduced being substantially pure. The so either in solid or molten form. The foregoing, however, is merely my theory, and I do not vWish to be limitedV thereto in any way.

lVhere the Word reaction occurs in the claims, unless qualified by the adjective di rect, or the like.. I .intend it to be understood that suchterm not only includes a simple or direct reaction but a complex re` action wherein possibly lseveral subsidiary reactions occur; this ously necessitated by the lack of exact lmmvledgel as to just hcw the molecules ot the swerr-.l elements involved behave with respect to each other. Where the alkali metal, for example, is used in the form of an alloy, it is still to be regarded as in the free Ior uncombined condition; being uncombined chemically; while this term obviously applies also to sodium or potassium vapor and the like. The term iron is to be regarded as otl suirlcient breadth to cover not only pure iron but also the iron present in cast iron, steel, or the like, since during the operation cast iron, for example, will speedily be deprived of its carbon, both combined and .lncf'mhined, and will be convert-ed to subst ally pure iron as described in in); ,i i application Serial No. f: and wle/tirer the iron be in the .i if pure ira-n and the carbon, mixed or -in contact ther-eig" b. be supplied from lin part at least as the source of carbon, in

either case theiron may properly be described as being iutuuately associatedvith carbon.

cyanogen compound as truly synthetic in character as may be commercially practicable. Finally, it should be stated that the hereindescribed process is so etlicient that nt such as petroleumv the yield of cyanid, for example, obtainable thereby is considerably in excess of titty per centA of' that theoretically possible. Indeed in somecases this yield closely approximates 100%. In other Words, it is possible to tix substantially all of the atmosphericA nitrogen introduced into the apparatus and to obtain not alone the cyanogen compound sought, but also substantially pure argon as a by-product, since the quantities of helium, xenon, krypton and neon, present in the argonare practically negligible. These gases too. are, so tar as is now known, absolutely inert andhence .behave in the same fashion as the argon,

in so far as` any commercial use of this mixture of inert gases is concerned.

It is possible to quantitively' combine substantially all sodium, carbon and nitrogen introduced into the apparatus, provided that' proper conditions-be observed and proper proportions of the constituent elements of the .cyanogen compound to be formed, be provided, and the liquid cyanid may then be drained or fiovved ott' from the residues of the reaction, or it may be removed from the iron, for example, by lixiviation or in 'any other desired manner. The product is quite free from sultids, ferro-cyanids and the like when the process is properly conducted.

WVhen the source of carbon is a hydrocar' bon such as petroleum oil or benzene, as previously indicated,. it is possible to operate the process very economically by utiizing the hydrogen given off from the reacting mass to obtain a fresh supply of nitrogen from the air, preparatory to repeating the cycle.' Thus:

This equation representing merely the result rather than the possible successive steps which may be involved.- Burning the hydrogen With air, We obtain atmospheric nitrogen, the oxygen combining of course with the hydrogen to form water, The nitrogen which remains may then be utilized in the process in the' manner previously described.

Having thus described my invention What I claim is:

1. A process for obtaining argon and rare atmospheric gases from the atmosphere which comprises treating air to substantially remove the oxygen content thereof and to leave substantially pure nitrogen mixed with argon, passing a current of this gaseous mixture through a heated reactive mass in Which is present a finely d I`died catalytic material intimately associate vith carbon and free alkali metal, to .combine substantially all of atmosphericl` gases which comprises subjectI lytic material which is intimately associated with carbon and there eifecting a reaction in which participate the said carbon, nitro# gen and an element capable of acting as the base of a stable oyanogen compound, to form said compound through the intermediacy of said catalytic material, and collecting the gaseous residues of said reaction.

3. A process of obtaining argon which comprises subjecting atmospheric nitrogen which is substantially free from uncombined oxygen but Which is still mixed With argon, to contact with an extended surface of a heated catalytic material which is intimately associated with carbon' and there 'effecting a reaction in which participate the said carbon, nitrogen and an initially free element capablev oi'- acting as the base of a stable' cyanogen compound, toform said compound through the interinediacy of said catalytic material, and collecting the gaseous residues of said reaction.l

4;. A process of obtaining argon and rare atinospheriogases AWhich comprises subjecting atmospheric nitrogen which is substan tially free from uncombined oxygen but Which is still mixed with argon, to contact with an extended surface of a heated cata lytic material Which isintimately associated with carbon and there effecting a reaction, at a temperature above 500 C. and below 1150o C., in which participate the said can bon, nitrogen and an element capable of acting as the base of ay stable cyanogen coinpound, to form said compound through the intermediacy of said catalytic material, and

collecting the gaseous residues of said reaction.

In testimony whereof l have aflixed my signature, in the presence of tivo Witnesses.

JoHN n. soenna,

Witnesses:

NORMAN E. Hom, THOMAS H. ROBERT. 

